Marvel’s space spectacular “Guardians of the Galaxy” introduces a passel of new heroes to the big screen.

There’s an animated talking raccoon, Rocket, whose sarcastic motormouth is voiced by Bradley Cooper. There’s also a walking, talking tree, with Vin Diesel in the recording booth, although the only words he ever says are “I am Groot.” Zoe Saldana, this time painted green instead of “Avatar” blue, is the alien assassin Gamora. And pro wrestler Dave Bautista plays the hulking, vengeful Drax the Destroyer.

The whole contentious pack is led — as much as it can be — by one Peter Quill, a strapping, half-human ne’er-do-well with a lithe yet muscular body who can dance as well as he can fight. He’s played in extreme Han Solo mode by Chris Pratt and …

Whoa, wait? Who? Chris Pratt? That flabby joker from NBC’s “Parks and Recreation”? How did he become a Marvel superhero?

He almost didn’t.

“When this role came around, I was reluctant,” the 6-foot-2-inch, 35-year-old Pratt admits. “I was having a bit of an identity crisis. I didn’t know what I was capable of doing, physically. And I didn’t think they would let me do what I really wanted, which is kind of a strange combination of drama and comedy. That’s how I figured I’d be at my best, but I thought they’d want me to play everything pretty straight. Which is fine, but I wanted to do something different.

“But then (director) James (Gunn) said to me, at the audition, ‘I’m just looking for somebody to own this.’ ”

Gunn had gotten Marvel’s blessing to imbue the action spectacular with the same skewed humor found in his indie films “Slither” and “Super.”

As wacky as “Guardians of the Galaxy” can get for a special-effects extravaganza about world-destroying plots, it also touches on the poignant, traumatic pasts of its little-known but very Marvelish protagonists.

As it turns out, Pratt had the perfect skill set for all of that. His comedy chops were on display in “Parks and Recreation” weekly, and his serious emoting abilities — as well as his ability to lose 30-plus pounds and muscle-up for a role — could be seen in “Moneyball” and “Zero Dark Thirty.” Gunn couldn’t have known at the time he hired Pratt, but the actor would later be associated with one of the most acclaimed movies of 2013, “Her,” and provide the lead voice for the biggest cartoon hit of 2014, “The Lego Movie.”

It might be argued that casting wasn’t as crucial to “Guardians of the Galaxy” as it has been for movies made about Marvel’s better-known characters such as Spider-Man, Iron Man, Captain America and Thor. They’ve been in comics for more than half a century, and while a version of the Guardians first saw print in 1969, it didn’t take off like other Marvel properties and was completely different from the team that will be seen on screen. These guys are more closely based on a comics series that ran from 2008 to 2010. It was a fanboy favorite, but again, nowhere near as well-known as Marvel’s previous movie subjects.

So, Gunn and company may not have had as many expectations to meet with their movie. They did, however, have the arguably tougher job of making the Guardians as engaging and memorable as the Avengers and X-Men of the cinematic universe. And that meant frontman Pratt had better deliver.

He was worried about that, too.

“I would’ve been completely happy spending the rest of my life doing sidekick characters, character roles,” Pratt admits. “I think they’re really fun, and there’s a certain freedom to being a character that you don’t get when you’re playing a leading man. I never really knew if being a traditional leading man was right for me.”

Then again, something inside Pratt made him have to do it. Born in Minnesota and raised northeast of Seattle, he’d had superheroes on the brain throughout his childhood, mainly because wherever he looked, he’d see one.

“I didn’t get so engrossed in the stories, but I really appreciated the art in comic books,” he recalls. “I was fascinated with the imagery, and my walls were covered with comic book hero murals. I had Punisher No. 29’s cover painted on my wall, and a Wolverine fighting Sabretooth that I painted myself. My brother had Spider-Man and Spawn down in his bedroom.

“We got to paint on our walls as kids if we wanted to. My dad was a remodeling contractor, so if they sucked, he had extra paint and we could just paint over them. We didn’t have a ton of money growing up, so we couldn’t afford all the best toys and fun things, but we got paper and pencils fairly cheap, and so we would draw.”

Though he went on to take some acting courses, Pratt split for Hawaii when he became an adult. Aspiring actors should not try this at home (Pratt’s abode was a van at the time), but that’s where he got his break. The actress Rae Dawn Chong visited the restaurant where he was working, Pratt pitched himself to her and she cast him in a movie she was about to direct. Soon after that, he was a regular on TV’s “Everwood” and “The O.C.”

And now he’s Star-Lord, the name Quill likes to call himself but no one else in the universe does. It means more to Pratt than just the dream-come-true of embodying one of his childhood walls.

“It means I can provide for my family for a while,” says Pratt, who has a 2-year-old son with his wife, Anna Faris, star of CBS’ “Mom.” “It means that I’ve redefined myself as an actor. It means that I can be, to a young generation, what Han Solo was to me as a kid.

“The thing that means the most is probably the idea that I can be a role model to young kids that are fans of this franchise. I’ll meet ’em and shake their hands and be a leader for them. I think that’s pretty cool.”

That may mean having to stay in shape, which took five months of training and dieting before “Guardians of the Galaxy” started shooting, and continued through another five of production.

Currently filming “Jurassic World,” next year’s long-awaited fourth entry in the dinosaur theme park film franchise, Pratt looks even more fit than he does in the Marvel movie.

“When I take care of my body, I feel good, and when I don’t, I don’t always feel great,” he admits. “But the trade-off is, I get to feel better around mealtime. Now, meals are not as exciting for me like they used to be. Anna likes to feed me, though.

“And listen, don’t blink: I’m gonna be fat again before you know it! As soon as I do enough of these ‘Guardians of the Galaxys’ for me and Anna to be living in a little house with a pond somewhere, I’ll be fat again.”

Bob Straus has been covering film at the L.A. Daily News since 1989. He wouldn't say the movies have gotten worse in that time, but they do keep getting harder to love. Fortunately, he still loves them.